The Fish Guru

Achieving Optimal Aquatic Plant Growth: Understanding the Estimative Index Method and PPM Calculations

Aquarium care and maintenance can be a challenging task, especially if you’re a beginner. One of the most critical aspects of maintaining a healthy aquarium is understanding how to provide the proper nutrients for your aquatic plants and fish.

This article will delve into two topics that will help aquarium owners maintain thriving aquatic plants in their tanks: the Estimative Index Method and Parts per Million (PPM) calculations.

The Estimative Index Method

The Estimative Index (EI) Method is a dosing method that provides nutrients to high-light tanks and heavily-planted aquariums. The EI Method requires dosing of fertilizers to pets based on estimations of required nutrients.

The method quickly replenishes nutrients after plants uptake nutrients, ensuring a continual availability of nutrients to the plants.

Who is the EI Method for?

The EI Method is specifically used for high-light tanks and heavily-planted aquariums. High-light tanks and heavily planted aquariums are known to consume significant amounts of nutrients, which they get from the water column.

Therefore, the EI helps provide nutrient ratios that ensure adequate plant growth and optimal aquatic health.

EI and Fish Safety

EI dosing is incredibly safe for aquatic life; however, EI can be harmful when dosages surpass what’s recommended, leading to toxic effects on your fish. Therefore you must always stick to the recommended dosage for your tank size.

Always ensure you’re maintaining nutrient levels within recommended limits, and water changes are conducted regularly. Regular water changes help maintain ranges within a safe zone that fish can endure.


When dosing fertilizers, it is essential to maintain recommended ppm of particular micro and macronutrients in the water column. PPM refers to parts per million of a nutrient in water.

Maintaining nutrients within the recommended ppm range is best for plant growth and optimal aquarium health. It’s important to be precise when dosing, as even a slight over or under dosage of nutrients can lead to nutrient imbalances or, worse, toxic effects on your aquatic life.

Always follow the recommended dosages, and use a reliable test kit to measure if the nutrient level in the water column is within the recommended range, adjusting your dosing rates accordingly. What is Nutrient Uptake?

Aquatic plants require several essential nutrients to grow and thrive. Nutrient uptake is the process of plants absorbing nutrients from the water column.

Nutrient uptake is a vital process that facilitates growth in aquatic plants.

What Affects Nutrient Uptake Rate?

Several critical factors influence nutrient uptake in aquatic plants. These factors include plant species, light intensity, carbon dioxide levels, and size.

Let’s discover the impact of each of these factors has on nutrient uptake.

Plant Species

Different aquatic plant species have differing nutrient requirements. For instance, some plants require significant amounts of potassium, while others require more phosphate.

Before deciding on the ideal aquatic plants for your aquarium, ensure you research and seek advice from experienced aquarium professionals on the necessary nutrients for those plants.

Light Intensity

Light is a critical factor in photosynthesis the process that aquatic plants require to survive and grow. Light intensity affects nutrient uptake in aquatic plants.

The higher the light intensity, the higher the nutrient uptake rate is due to increased photosynthesis. Ensure your aquarium has sufficient lighting for your plant species.

Carbon Dioxide (CO2)

CO2 is one of the essential nutrients required for plants to grow in optimal conditions. Plants absorb CO2 from the air to form glucose and other essential compounds necessary for plant growth.

Maintaining optimal levels of CO2 helps support photosynthesis and growth.


Aquatic plants’ size determines their nutrient uptake rate. Nutrient uptake usually increases with plant size in most aquarium plants.

Therefore, it is essential to ensure that you don’t keep your aquatic plants in restrictive containers that limit their growth.

PPM Calculation

As earlier mentioned, PPM refers to the amount of a nutrient in a particular volume of water. PPM is an essential consideration when dosing fertilizers.

Therefore, calculating PPM is crucial for those aiming to balance nutrient levels in their aquariums. To calculate PPM, you need to know the concentration of the solution and the sample size.

PPM is calculated by dividing the mass of the solute by the volume of the solution. In conclusion, understanding how to provide the proper nutrients for your aquatic plants and fish is vital to maintain optimal aquatic life in your aquarium.

The Estimative Index Method helps provide nutrients to high-light tanks and heavily-planted aquariums. Similarly, when dosing fertilizers, PPM calculations are necessary, and nutrient uptake rate is crucial to plant growth.

By applying the principles discussed in this article, you’ll be well on your way to having healthy, thriving aquatic plants.

3) The Goal of EI Nutrient Dosing

The goal of EI nutrient dosing is to supply the necessary nutrients to the aquatic plants in your tank continually. Doing so encourages steady, healthy plant growth that outcompetes any algae.

That is because when plants have their nutritional demands met, they absorb nutrients from the water column efficiently, and that starves algae of nitrogen, phosphorus, and other elements required for algae growth. Too much or too little nutrients can lead to algae blooms, which is why it’s essential to adhere to recommended dosage rates.

Recommended Dosage Rates

To maintain the recommended levels of nutrients, it is necessary to dose adequately. EI dosing fertilizer involves using macro-nutrients such as potassium nitrate, potassium phosphate, and magnesium sulfate and micro-nutrients such as trace elements to feed your plants.

The following are common macro-nutrient dosages for a fifty-gallon aquarium:

– 1/4 tsp of potassium nitrate three times a week

– 1/16 tsp of potassium phosphate three times a week

– 1/4 tsp of magnesium sulfate three times a week

For the micronutrients, one can use a commercial mixture or individual fertilizers to supplement the aquarium. It is recommended to dose micronutrients about two to three times a week.

However, it is important to note that actual dosages may vary depending on your aquarium’s unique needs.

4) What You Need to Use This Method

Using the EI nutrient dosing method requires a few essential items.

Macro-nutrients for Plant Growth

Macro-nutrients such as potassium nitrate, potassium phosphate, and magnesium sulfate are essential for plant growth. Potassium nitrate provides the necessary nitrogen and potassium, while potassium phosphate provides more phosphate.

Magnesium sulfate provides magnesium and sulfur, important for chlorophyll creation and enzymatic processes such as photosynthesis.

Micronutrients for Plant Health

Micronutrients, aka trace elements, are also essential for plant health. They include minerals like iron, copper, and zinc, which play critical roles in enzymatic functions, respiration, and photosynthesis.

You can use either a commercial fertilizer mix that has trace elements or add individual ones. Dosage rates are typically lower than those of the macro-nutrients, with tap water often containing sufficient amounts of some micronutrients.

Dosing Equipment

Dosing equipment is also a must-have when using the EI nutrient dosing method. To ensure proper and accurate dosing, you’ll need measuring spoons, a scale, bottles, a funnel, and dosing containers.

Dry Fertilizer: Using dry fertilizer for dosing the aquarium is the most common method. Since fertilizer is easier to store and distribute in this state, it is the most convenient way to dose.

Dry fertilizer usually comes in powdered form, which is easy to measure and dose. Measuring Spoons: Measuring spoons help ensure that the correct quantity of fertilizer is added to the aquarium.

Scale: A scale helps in accurately weighing the quantity of fertilizer to be dosed. Bottles:

Dosing bottles help manipulate the precise amount of fertilizer to be added to the aquarium, ensuring you dose your aquarium consistently.

Funnel: A funnel helps in minimizing spills when pouring fertilizer into a container.

Dosing System: Automated dosing systems can also be used for accuracy and convenience. It allows for dosing of multiple nutrients at precise intervals to maintain a stable nutrient balance in the tank.

Aquarium Lighting

To ensure optimal plant growth, it is crucial to have adequate lighting in your aquarium. For high-light plants such as carpeting plants to grow correctly, you’ll need strong lighting system.

Aquarium lighting plays a critical role in providing the right light spectrum for photosynthesis, allowing plants to use their provided nutrients effectively. Insufficient lighting leads to slow plant growth and can be counterproductive in the long run.

CO2 Injection

Carbon Dioxide (CO2) injection is an optional but highly recommended step to promote healthy plant growth. CO2 injection helps provide readily available carbon to plants to fuel photosynthesis.

A pressurized CO2 system or diffuser is used to dissolve the CO2 gas into the water column. The higher the carbon dioxide levels, the higher the plants’ nutrient uptake rate.

However, CO2 injection may not be necessary for low-light planted tanks.

Water Hardness

Water hardness is a measure of the dissolved minerals in your water, which affect the suitability of your aquarium as a habitat for aquatic life. It refers to two types of minerals that cause hardness: carbonate hardness (KH) and general hardness (GH).

Overall, tap water hardness should be known, and adjustments should be made to ensure an optimal environment for the growth of aquatic plants without risking livestock health. If your tap water is very hard, it might be necessary to use a Reverse Osmosis (RO) unit to reduce excess mineral content.

In conclusion, the EI nutrient dosing method is highly effective in providing your aquatic plants with the nutrients necessary for sustained growth and outcompeting algae. However, it is essential to use the recommended dosage rates and have all the necessary equipment and adequate lighting.

A balanced nutrient solution that sustains your plants and keeps aquatic creatures healthy is possible with the right information, equipment, and dosage discipline.

5) How to Dose with this Method

The first step to dosing with the EI nutrient dosing method is to solidify a dosing regimen. There are two options for dosing- daily and weekly dosing.

Daily dosing is performed daily by adding micro-nutrients and dosing macro-nutrients every other day. Daily dosing is recommended for high light tanks or heavily planted aquariums with constant nutrient demand.

Weekly dosing is the most common method of dosing. Nutrients are added in larger quantities once a week, ensuring a constant supply of nutrients in the aquarium.

Dosing of macro-nutrients and micro-nutrients in EI nutrient dosing is integral to aquatic plant growth. Macro-nutrients are added three times a week, while micro-nutrients are added two to three times a week.

Due to the complexity of dosing, the dosages have to be precise and consistent. It is also essential to note that overdosing of macro-nutrients can lead to algae blooms or deficiencies, while an overdose of micro-nutrients is toxic to fish.

Water Changes

Water changes can help reset nutrient concentrations to keep them within the recommended range. Weekly water changes are recommended to avoid the buildup of excess nutrients in the aquarium.

It is recommended to perform a 30% water change weekly and replace the filtered water with newly treated tap water within the recommended range. Water changes also help remove algae spores, which may flourish when the nutrient concentration is high.

How to Perform a Water Change

Performing water changes is simple and essential to maintaining a healthy aquarium. Here are the steps to performing a water change:


Vacuum the substrate to clean any debris. 2.

Trim any dead leaves or plants overgrowth. 3.

Remove approximately 30% of the water using a siphon.


Refill the tank with freshly dechlorinated tap water, maintaining the recommended temperature and with water parameter within the recommended range.


The EI and PPS (Perpetual Preservation System) methods are two popular nutrient dosing methods in the aquarium hobby. Both methods aim to provide optimal nutrient levels in the aquarium.

The difference between EI and PPS is in the dosing method and the nutrient levels supplied. The EI method uses large doses of macro-nutrients and micro-nutrients.

The doses provided exceed the needed nutrient requirements, and the plants absorb what they need, ensuring there is no deficiency. With the EI method, it’s easier to maintain nutrient concentration and avoid nutrient deficiency.

The PPS method, on the other hand, uses smaller doses of macro-nutrients and micro-nutrients, typically three times a week. That provides a more controlled and precise nutrient balance.

Ultimately both methods aim to provide adequate nutrient levels; the choice in which to use relies on personal preferences and the unique conditions for specific aquariums.

6) EI Aquarium Calculator

EI aquarium calculator is a tool for calculating fertilizer dosages needed for plants in your aquarium. It is a simple and easy tool that takes the guesswork out of calculating dosages.

The calculator works by using the size and type of your aquarium to calculate the amount of macro-nutrients and micro-nutrients your plants require.

The EI aquarium calculator gives simple dosage information for both macro-nutrients and micro-nutrients according to the weekly dosing regime.

It eliminates the need to calculate complicated percentages and other calculations used in the EI method. The calculator is available online as an app or can be downloaded as an excel spreadsheet.

In conclusion, utilizing the EI Nutrient dosing method to fertilize your planted aquarium is a significant investment but can pay-off in healthy and thriving plant life. Maintaining necessary nutrient levels, water parameters, and dosages can be a complex and time-consuming process.

However, utilizing a handy tool such as an EI aquarium calculator can simplify the process. Ultimately, finding a nutrient balance that works best for your aquarium takes time, effort, and experimentation, but it’s worth the reward of a beautiful and thriving planted aquatic system.

In conclusion, the EI Nutrient

Dosing method is an excellent way to maintain healthy aquatic plants in your tank by continuously providing the necessary nutrients. It utilizes macro and micro-nutrients dosages to supply adequate nutrition required by the plants.

However, maintaining the correct dosage rates and water parameters is crucial in preventing nutrient imbalances and potential health issues. Regular weekly water changes, careful monitoring, and use of dosing tools such as an EI aquarium calculator can significantly aid in nutrient management.

With the right tools, time, and efforts, maintaining a lush and healthy aquatic plant environment can be a rewarding experience for all aquatic hobbyists.

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